Wireless signaling system



W. C. WHITE.

WIRELESS SIGNALING SYSTEM. APPLiCATlON FILED'JAN.18. 1917.

Fig-I.

Inventor: Walham CWnite,

His fittorne g.

pling between the two circuits which is'al-- UNITED ST P oriucn.

WILLIAM C. WHITE, 0F SCHEN'ECTADY, NEW YORK, ASSIGNOR '10 GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

wmnnnss SIGNALING SYSTEM.

Specification of Letters Patent.

Application filed January 18, 1917. Serial No. 143,045.

charge controlling member or grid inclosed in an evacuated envelop may be employed for producing radio frequency oscillations. In order to secure this result a source of energy is placed in the plate circuit of the device which includes the cathode and anode and an inductance, and this circuit is coupied with the grid clrcuit which includes the cathode and grid and a second inductance. If a suitable degree of coupling-is provided between the two circuits enough energy is transferred from the plate circuit to the grid circuit to impress upon the grid the potential necessary to control the flow of current in the plate circuit in the desired manner. In some cases the electrostatic couways present by reason of the capacity between the electrodes. is suflicient to bring about the desired result. In other cases this coupling is supplemented in various ways, as for example, by-a coupling between the inductances in the two circuits, or by an additional electrostatic couplingconsisting of a condenser between the grid and anode or by a combination of the two forms of coupling. Because of the unidirectional conductivity of the electron discharge device the current in the plate circuit will usually be pulsating in character. For prac-. tical purposes, however, it may be considered as being made up of two components, one a constant direct current and the second an alternating current superimposed upon the direct current. order to utilize this alternating component in an antenna it has been customary to couple a coil in the antenna with the plate circuit inductance. It has, however, been suggested'that. the

system might be simplified by including the plate circuit inductance directly in the an tenna circuit and thus impressing the alternating component of the plate current upon the antenna, thereby avoiding the necessity of an inductive coupling between plate circuit and antenna, and the use of a separate coil with-the unavoidable losses therein. In the practical application of this arrangement, however, it has been found that the source of potential used for heating the cathode, together with the auxiliary apparatus used for controlling the heating current, instead of being at a fixed low potential with respect to earth, as is usual in the prior arrangement, is at a potential which alternately varies at the frequency generated between positive and negative values with respect to earth, and that this potential may rise to such a high value that it becomes inconvenient to insulate from earth the source which furnishes the heating current.

One of the objects of my invention is to provide a connection whereby this disad vantage may be avoided and the advantage of the direct connection of plate inductance .to the antenna may be retained. A

In order to attain this object I divide the. plate circuit inductance into two parts and arrange the two parts insuch a way that they furnish two parallel paths for the high frequency component of the plate current. One of these inductances is included directly in the antenna circuit and the second inductance is so closely coupled to the first that for all practical purposes it ,maybe considered as being directly in the antenna circuit. The source of current for heating the cathode is connected to the ends of those inductances which are always at a low potential with respect to earth in such a way that the heating current flows through the two inductances in'series. As a result the source which furnishes the heating current and the auxiliary regulating apparatus will i always be at a low earth.

In order to utilize the continuous radio frequency oscillations, produced by the arpotential with respect to v provide a simple and eflective means for automatically breaking up the oscillations inthis way when it is desired to transmit telegraphic signals.

In accomplishing this result I provlde means for short circuiting one of the induct-ances employed, at regular intervals, and thereby interrupting the production of oscillations. With this arrangement the device normally impresses radio frequency oscillations upon the antenna and when signals are sent the oscillations are broken up into groups of an audible frequency. The same effect may also be secured by arranging the apparatus in such a way that one of the circuits is normally open and hence no oscilla:

- tions are produced. By alternately closing and opening the circuit at regular intervals groups of oscillations may be produced at an audible frequency.

My invention will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 shows diagrammatically one embodiment of my invention, and

2 shows a modification thereof.

indicated in the drawing, an electron discharge device is used which comprises an electron emitting cathode 1 of filamentary form, a plate shaped anode 2, and a grid 3 5 and 6 in order to reduce the voltage which will be applied to' the terminals of, the cathode. The value of the heating current is regulated in the usual manner by varying the resistance in the circuit by means of the, variable connection 9. A condenser 10 which is in series with inductance 6 in the plate circuit serves as a low resistance path for the alternating component of the current flowing through the inductance 6, and as an open circuit to the direct current used for heating the cathode. The grid circuit comprises an inductance 11 and may also include a battery 12 for the purpose of giving the grid a normal potential at which the device operates most efficiently. The antenna 13 is connected to a suitable point, such, for example, as the point 14: in the inductance l1, and variations in the tuning of the system and in the potential impressed upon the antenna may be brought about by varying the point of connection of the antenna. The antenna is grounded through inductance 5 and a condenser 15. The object of this condenser is adapted to to avoid connecting the source 7 direct to earth. If there is no objection to such a connection the condenser 15 may be omitted. With the connection described the grid and plate circuits are coupled electrostatically by reason of the capacity between the elec trodes 1, 2 and 3, and this coupling is supplemented by the capacity of the antenna which is, in effect, connected between the grid 3 and anode 2. The coils, 5, 6 and 11 may also be arranged to furnish any desired degree of inductive coupling between the two circuits.

The arrangement thus far described is roduce radio frequency continuous oscil ations, the frequency of which will be determined by the natural period of the antenna system. In order to interrupt these oscillations at regular intervals when it is desired to send signals, I provide an auxiliary circuit includin a key 16 which is normally open and a Tmzzer consisting .of a coil 17 controlling an armature 18,

which makes a contact at 19 when the coil 17 is not energized. A small portion of the potential across resistance 8 is utilized for operatin the buzzer, the potential used being regu ated by the sliding contact 20. As long as the key 16 is open this auxiliary circuit isopen and oscillations will be produced, When the key 16 is closed however the inductance 6 is short circuited and the oscillations will immediately stop. The coil 17 will then be energized and contact broken at 19, the auxiliary circuit thus being opened allowing the oscillations to start again. At the same time coil 17 will be deenergized and contact 19 will again close and the oscillations be interrupted. This action will continue as long as the key 16 is closed'and by proper adjustment of the buzzer the interruptions may be made to occur at any frequency desired. As a result continuous oscillations will be produced in the antenna in groups as long as the key 16 is depressed and these groups may be pro duced at any audible frequency desired by varying the adjustment of the buzzer. The length of each group of oscillations and the length of the period between groups may also be varied by varying the adjustment of the buzzer.

The arrangement shown in Fig. 2 diflers from that shown in Figvl merely in the arrangement of the auxiliary circuit for controlling the oscillations. In this case the rid circuit is so arranged that the device -1s normally inoperative for producing oscillations. When the key 16 is-depressed the gridcir'cuit is closed through the key and contact 19 and oscillations are produced. At the same time the coil 17 is energized and the contact broken at 19- and oscillations are thereby interrupted. A portion of the battery 12 in the grid circuit may be utilized for operating the buz zer, variable connec-- modifications in the specific arrangement of the oscillation controlling means may be made without departing from the scope of my invention. Instead of short circuiting *the inductance in either the grid or plate circuit in the general manner indicated in Fig. 1 to stop oscillations the connections may be made in such a wa as to open one of the circuits to accompllsh the same re.-

sult by an arrangement of the general type shown in Fig. 2. v V

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination in a wireless signaling system of an antenna, an electron dlscharge devlce connected to said antenna and having plate and grid circuits so adjusted an device connected to said antenna and havingplate and grid circuits so adjusted and coupled to each other that radio frequency continuous oscillations will be produced in said antenna and means operatively related to the plate circuit for intermittently short terrupting the production of;oscillations.

3. The combination in a wireless signaling system of an antenna, an electron discharge device connected to said antenna and. having plate and grid circuits containing inductancesand so adjusted and coupled to each other that radio freque'ncycontinuous oscillations will be. produced in said antenna, and

means for intermittently short circuiting one of said inductances and thereby interrupt ng the production of oscillations at an aud ble frequency.

circuiting a portion thereof and thereby inp the cathode to 4. The combination in a system for producing alternating currents of an electron discharge device comprising a cathode adapted to be heated to incan escence, acooperating anode and a grid inclosed in an evacuated envelop, two inductances connected 1n the late circuit of said device in such a way t at alternating current produced in the circuit will flow through the two in parallel, andthat the current necessary for heating the cathode to incandescence fwill flow through the two in series, and a grid circuit containing an inductance and vcoupled to the plate circuit in such a manner that radio 'frequency currents will be produced in the plate circuit.

5. The combination in a wireless signaling system of an antenna, an electron discharge device connected to said antenna and having plate and grid circuits containing inductances and so adjusted and coupled to each other-that radio frequency, continuous currents will be produced in said antenna, the in ductance int e plate circuit comprising two coils inductively related to each other and so connected that the radiofrequency currents flow through the two inparallel, and means for intermittently short-circuiting one of said coils and thereby interrupting the production of. oscillations at an audible frequency.

6. The combination in a wireless signaling system of an antenna, an electron discharge device connected to said antenna and comprising a cathode adapted to be heated to incandescence, a cooperating. anode and a grid inclosed in an evacuated envelop, two inductances connected in the plate circuit of said devicein such 'a way that alternating currents produced in theplate cir- I cuit will flow through the two in parallel, and that the current necessary for heating incandescence will flow through the two in series, a grid circuit containing inductance and coupled to the plate circuit in such a way that radio frequency continuous oscillations will be produced in the antenna and means for intermittently short circuiting one of the inductances of the system and thereby interrupting the production of oscillations atan audible frequency.

In. witness whereof, I havehereunto set my hand this 17th day of January, 1917.

' WILLIAM G. WHITE. 

